JPH0472853B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a rubber compound that has excellent adhesion to different materials. More specifically, the present invention relates to a rubber composition with excellent adhesive properties obtained by blending a diene liquid rubber having a hydroxyl group with natural rubber or synthetic rubber. Rubber products such as tires, belts, hoses, and rubber rolls are now required to have high performance and functionality, and efforts are being made to combine them with different materials such as natural and synthetic fibers, synthetic resins, and metals. , adhesion between rubber and these materials is often a problem. Conventionally, in vulcanization bonding between unvulcanized rubber and different materials, there have been methods using rubber adhesives, methods of kneading certain compounded chemicals that contribute to adhesion into the rubber, or methods of pre-treating different materials with adhesives. Methods such as this are widely adopted. On the other hand, when it comes to vulcanized rubber and different materials, it is difficult to obtain strong adhesive strength using the above-mentioned bonding method used for unvulcanized rubber, and various methods have been proposed to solve this problem. That is, methods are known in which the adhesive strength is improved by physically buffing the vulcanized rubber surface or forming minute irregularities on the surface to increase the adhesive area. However, although some effects are observed at room temperature, there is almost no effect of improving adhesive strength at high temperatures. On the other hand, methods are also known in which the adhesive strength is improved by chemically oxidizing the rubber surface with a strong acid or treating it with a halogen compound to add halogen to the rubber surface. In chemical methods, the chemicals used are often dangerous and difficult to handle, and post-treatments such as washing with water and drying are often required, making the process complicated to implement industrially. . As a result of extensive research into a rubber composition that does not have the above-mentioned drawbacks and has excellent adhesive strength, the present inventors have found that a diene-based liquid rubber having three or more hydroxyl groups in one molecule is added to natural rubber or synthetic rubber. By blending the vulcanized rubber and dissimilar materials, it is possible to obtain a composition that does not require the above-mentioned post-treatment, improves the adhesive strength at room temperature, and at the same time has excellent adhesive strength even at high temperatures. The present invention was based on the discovery that the present invention is possible. That is, according to the present invention, a butadiene or isoprene polymer, or a butadiene-isoprene copolymer having three or more hydroxyl groups in one molecule, and 10,000 to 150,000 parts by weight of natural rubber or synthetic rubber, A rubber composition having excellent adhesive properties can be obtained by blending 3 to 45 parts by weight of a diene liquid rubber having a molecular weight of . The diene liquid rubber used in the present invention is a polymer or copolymer of butadiene or isoprene, and has three or more hydroxyl groups in one molecule of the (co)polymer. Note that the liquid rubber may be copolymerized with a component other than the diene monomer, such as a vinyl compound such as styrene, to the extent that the gist of the present invention is not impaired. Note that, for the purpose of the present invention, isoprene-based rubber such as isoprene rubber or isoprene copolymer rubber containing isoprene as a main component is most suitable. In the present invention, the hydroxyl group may be added at either the end of the molecule or in the molecular chain, but it is necessary to have three or more hydroxyl groups in one molecule. If the number is less than 3, a sufficient effect of improving adhesive strength will not be exhibited and it will not be suitable for the purpose of the present invention.
In addition, if the number is too large, the liquid rubber may become too hard and the compatibility with the rubber to be compounded may be insufficient, resulting in adverse effects such as loss of physical properties, so the number should generally be within 20. is appropriate. In particular, when it has 5 to 10 hydroxyl groups, the intended purpose of the present invention can be easily achieved. Further, in the present invention, the liquid rubber has a viscosity average molecular weight of the liquid rubber before introducing hydroxyl groups.
10,000 to 150,000 are used. molecular weight
If it is lower than 10,000, the co-vulcanization with the compounded rubber will be significantly reduced, and not only the adhesion but also the physical properties of the rubber itself will be significantly deteriorated. Also, the molecular weight
If it exceeds 150,000, it becomes difficult to mix and disperse into rubber, which is not preferable. From this point of view, the molecular weight is 15,000~
A value in the range of 70,000 is more preferably used. Further, in the present invention, the microstructure of the liquid rubber is not particularly limited, but it is not preferable to have a large amount of vinyl bonds from the viewpoint of compatibility with rubber and co-vulcanization. % or less. Such diene-based liquid rubber can be produced by polymerizing diene-based monomers such as butadiene or isoprene using a radical generator containing hydroxyl groups such as hydrogen peroxide, or by radical polymerization or anionic polymerization of diene-based polymers that do not contain hydroxyl groups. A method is adopted in which a hydroxyl group is introduced through a post-reaction. Examples of post-reactions include a method in which an epoxy group is introduced using hydrogen peroxide and a carboxylic acid, followed by hydrolysis to form a hydroxyl group, or a method in which maleic anhydride is added and further modified to introduce a hydroxyl group. Among these, a method of adding maleic anhydride or a derivative thereof and further modifying it to introduce a hydroxyl group, especially a method of adding maleic anhydride and then adding a hydroxyl group to the general formula
A method in which an amino alcohol represented by H ₂ N-R-OH (wherein R represents an alkyl group, an aryl group, or an aralkyl group) is reacted is preferred and will be described in detail below. Any known method can be adopted for the reaction of diene-based liquid rubber with maleic anhydride or a maleic anhydride derivative such as maleic acid or maleic acid ester, that is, the maleation reaction. A method of reacting with maleic anhydride by heating, mixing and stirring is preferably employed. For this reaction, it is also possible to use a catalyst such as a peroxide or an azo compound, and it is also possible to use an inert hydrocarbon solvent such as hexane, toluene or benzene. It is also possible to carry out the reaction in the presence of an antigelation agent such as acetylacetone or acetylacetone. The reaction temperature is preferably 100 to 250°C, and the reaction time is preferably 1 to 20 hours. The amount of maleic anhydride or its derivative added is required to be 3 moles or more per molecule of diene liquid rubber. The maleic anhydride-modified diene liquid rubber thus obtained is reacted with amino alcohol,
That is, it is subjected to an amidation reaction or a subsequent dehydration reaction leading to imidization. The amino alcohol used here is represented by the general formula H ₂ N-R-OH (in the formula, R represents an alkyl group having 1 to 20 carbon atoms, an aryl group, or an aralkyl group), and representative examples include Examples include ethanolamine, 1-aminopropan-2-ol, 2-aminopropan-1-
ol, 1-aminobutan-2-ol, 2-aminobutan-1-ol, 3-aminobutan-1
-ol, 1-amino-2-methylpropane-2
-ol, 1-aminopentan-4-ol or 1-aminopentan-5-ol, or aminoaralkyl alcohols such as aminophenol, aminocresol, aminoxylenol or aminonaphthol. Among them, aminoalkyl alcohols are preferably used. For this reaction,
It is necessary to pay sufficient attention to the reaction temperature. In other words, the acid anhydride group in the diene liquid rubber modified with maleic anhydride easily reacts with the amino alcohol to form a semi-amidated product, but if the reaction temperature is too high at this time, a gelation reaction or other undesirable side effects may occur. A reaction occurs. Therefore, during the second half of addition of amino alcohol, the reaction temperature should be kept low until the amide is completed.
Specifically, room temperature to 130℃, particularly preferably 50 to 100℃
It is necessary to carry out the test at ℃. On the other hand, the dehydration reaction of imidization subsequent to amidation needs to be carried out at a higher temperature than the amidation reaction. At this time, if the temperature is too low, imidization will not occur, and carboxyl groups will remain in the modified diene liquid rubber finally obtained in the present invention, often resulting in unfavorable reactions with the crosslinking agent. Become. From this point of view, this dehydration reaction is carried out at 150-220℃, preferably
It is better to do it at 150-180℃. During this dehydration reaction, a dehydrating agent such as sulfuric acid, phosphoric acid, or phosphorus pentoxide may be used to accelerate the reaction, or a means of distilling off the water produced under reduced pressure may be used. good. The amount of amino alcohol used is in most cases about the same number of moles to three times the number of moles of maleic anhydride added in the maleic anhydride-modified diene liquid rubber. In this way, a modified diene liquid rubber to which N-hydroxyhydrocarbyl-maleimide is added, that is, a diene liquid rubber having a hydroxyl group in the molecule is obtained. In addition, the synthetic rubbers used in the present invention include isoprene rubber (IR), styrene-butadiene rubber (SBR), butadiene rubber (BR), nitrile rubber (NBR), chloroprene rubber (CR), and ethylene propylene rubber (EPDM). Among these synthetic rubbers and natural rubbers, one or more types are selected and used as a mixture. The diene liquid rubber having a hydroxyl group may be used in an amount of 3 to 100 parts by weight of natural rubber or synthetic rubber.
It is used in an amount of 45 parts by weight. If the amount is less than 3 parts by weight, a sufficient effect of improving adhesive strength cannot be obtained. On the other hand, even if it is added in excess of 45 parts by weight,
The effect of improving adhesive strength is not as great as when a smaller amount is blended, and the physical properties such as the strength of the rubber are undesirably reduced too much. From this point of view, the blending amount is more preferably in the range of 5 to 20 parts. The effects of the rubber composition of the present invention can be further enhanced by incorporating a filler containing silicon dioxide. A filler containing silicon dioxide is a material containing silicon dioxide as one of its components, and includes silicas such as hydrous silicic acid and anhydrous silicic acid, and clays such as kaolin, calcined clay, pyroferite, and montmorillonite. These fillers may be used alone or in combination of two or more. The blending amount is preferably 5 parts by weight or more per 100 parts by weight of natural rubber or synthetic rubber. If the amount is smaller than that, the effect of the filler cannot be obtained. The composition of the present invention may be used by blending various other compounding agents commonly used in the rubber industry. Examples include reinforcing agents and fillers such as carbon black calcium carbonate and magnesium carbonate, vulcanization accelerators such as zinc oxide, magnesium oxide, and stearic acid, crosslinking agents such as vulcanization accelerators, sulfur, and organic peroxides. agent, anti-aging agent, oil, softening agent such as polybutene, etc. In some cases, it is also possible to use a diene liquid rubber that does not contain hydroxyl groups as a softener. Additionally, the composition of the present invention has secondary effects such as improved extrusion moldability, improved processability such as roll winding and calendaring properties, and improved workability such as bonding of unvulcanized fabrics together. It also shows the effect. The composition according to the invention can be applied to metals, natural and synthetic fibers, polyvinyl chloride, as well as other rubber compounds.
Greatly improved adhesion to different materials such as polyurethane and other synthetic resins has made it possible to use tires, belts,
Suitable for use in hoses, rubber rolls, footwear, etc. EXAMPLES Next, the present invention will be specifically explained with reference to Examples, but the present invention is not limited thereto. Example 1 The four types of formulations shown in Table 1 were kneaded with a roll, formed into a sheet, and press-vulcanized at 160° C. for 25 minutes in a 2 mm thick sheet mold. Then,
After wiping and cleaning the surface of this vulcanized rubber sheet with toluene, a two-component urethane resin solution (Coronate
4095/TDI (100/3): Manufactured by Nippon Polyurethane Co., Ltd.)
3000d warp x 2000d weft (number of strokes, both length and width, 12
A polyester woven fabric of 100 mm/inch) was layered, and then a urethane solution was applied on top of the woven fabric so that the urethane was sufficiently impregnated into the fibers. The laminated sheet was dried and the solvent was evaporated. Next, a previously press-molded soft vinyl chloride resin sheet was layered on the woven fabric layer of this laminated sheet, and the sheet was pressed at 200° C. for 5 minutes using a press, and then cooled. This laminated sheet was cut to a width of 25 mm according to the method of JIS K-6301, and a peel test was conducted between the rubber sheet layer and the thread layer using a tensile tester at a speed of 50 mm/min at 25°C and 60°C.
I did it at ℃. The results are shown in Table-2. The hydroxyl group-containing liquid polyisoprene rubber used in this example was prepared by reacting a high cis-1,4-polyisoprene rubber with a viscosity average molecular weight of 25,000 with maleic anhydride and then with an amino alcohol to undergo a dehydration reaction. It has six hydroxyl groups in one molecule. Further, the liquid polybutadiene having hydroxyl groups at both ends used as a comparative example had a molecular weight of 2800 and had two hydroxyl groups at the ends of the molecule.

[Table] As shown in Table 2, in terms of peel strength at 25°C, the adhesive strength of the examples according to the present invention is greatly improved. Furthermore, systems using a silica-based filler in combination showed improvement compared to general. The measurement results of adhesive strength at 60°C also showed a similar trend, indicating an improvement in heat-resistant adhesive strength. On the other hand, the adhesive strength of the comparative example is rather lower than that of the control example.

[Table] Example 2 The three types of blends shown in Table 3 were kneaded using a roll, and then rolled into a sheet with a thickness of about 6 mm. On the other hand, an iron plate with a thickness of 2 mm, a length of 60 mm, and a width of 25.4 mm was polished by sandblasting, washed with a solvent, dried, and then treated with epoxy resin (Araldite).
AW2108, hardening agent HW2951 (Ciba Geigy) 1
(mixed in a ratio of 1:1) was applied onto an iron plate using a spatula. An epoxy resin-coated iron plate was fitted into a JIS K-6301 specification mold, and a rubber sheet cut to a predetermined size was vulcanized in a stack press at 160°C for 20 minutes. This vulcanizate was then subjected to a 90° peel test according to JIS K-6301. The results are shown in Table 4. The hydroxyl group-containing liquid polyisoprene rubber used in this example was prepared by reacting an unmodified liquid polyisoprene rubber with a viscosity average molecular weight of 25,000 with maleic anhydride and then with an amino alcohol. It has 3.4 hydroxyl groups in the molecule.

【table】

[Table] As shown in Table 4, the adhesion was greatly improved by blending hydroxyl group-containing polyisoprene rubber, and the adhesion was further improved by blending silica.

[Table] Peeling condition Rubber to resin Rubber to resin to metal Resin to metal
Interfacial peeling Interfacial peeling Interfacial peeling

Claims (1)

[Claims] 1.1 per 100 parts by weight of natural rubber or synthetic rubber.
An adhesive compounded with 3 to 45 parts by weight of a diene liquid rubber having a molecular weight of 10,000 to 150,000, which is a butadiene or isoprene polymer having three or more hydroxyl groups in the molecule, or a butadiene-isoprene copolymer. A rubber composition with excellent properties. 2 10,000 or more with 3 or more hydroxyl groups in one molecule
A diene liquid rubber having a molecular weight of 150,000 is obtained by adding maleic anhydride or a derivative thereof to a liquid rubber of butadiene or isoprene polymer or butadiene-isoprene copolymer, and then reacting with an amino alcohol. The rubber composition according to claim 1, which is a modified product. 3. The rubber composition according to claim 1, wherein the filler in the rubber composition is a filler containing silicon dioxide.